제1세대 니켈계 단결정 초합금인 CMSX 6를 사용하여 셀렉타법으로 진공 정밀주조하여 단결정을 제작하였다. 주형온도 약 1500˚C, 주입온도 약 1630˚C와 용탕 주입 직후 주형을 2.5mm/분 속도로 하강시켜 단결정을 성장시켰다. 단결정 주조조직에서 기지와 공정조직은 γ' 석출물(Ni3(Al, Ti)) 모양과 크기에 따라 각각 모두 두영역으로 구분되었으며, 공정조직의 Ti함랗은 기지보다 높았다. 즉, EPMA 및 CBED 분석 등으로 γ' 석출물을 분석한 결과, 기지내의 γ'은 크기가 0.5~0.7μm 이하이며 화학조성상 Ni3Al에 가까웠으며 격자구조도 Ll2를 나타내었다. 반면에 공정조직에 가까울수록 γ' 크기는 1.0μm보다 컸으며, 모양도 판상형의 거대한 모양으로 바뀌었다. 화학조성 또한 Ni3Ti에 가까웠으며 격자구조도 D O24를 나타내었으므로 수지상과 공정조직의 γ' 석출물은 화학조성 및 격자구조가 상이함을 알 수 있었다.

This study was conducted to investigate the distribution characteristics, source identification, and health risk of polycyclic aromatic hydrocarbons (PAHs) present in particulate matter 10 (PM-10), in Gwangju. PM-10 samples were collected from September 2021 to August 2022 from three sampling sites, one located in each of the following areas: green, residential, and industrial. The average concentrations of PAHs were found to be higher in the industrial area (9.75±6.51 ng/㎥) than in the green (6.90±2.41 ng/㎥) and residential (6.74±2.38 ng/㎥) areas. Throughout the year and across all sites, five-ring PAHs accounted for the largest proportion (29.8–34.5%) of all PAHs. The concentrations of PAHs showed distinct seasonal variations, with the highest concentration observed in winter, followed by autumn, spring, and summer. Source apportionment analyses were performed using diagnostic ratios and principal component analyses, which indicated that coal/biomass combustion and vehicle emissions were the primary sources of PAHs in PM-10. The incremental lifetime cancer risk was estimated for all age groups at all sampling sites, and the results revealed a much lower risk level than the standard acceptable risk level (1×10-6).

This study was conducted to propose a way to increase the accuracy and precision of β-ray measurement equipment. Statistical processing results of equivalent evaluation data from 2016 to 2021 confirmed that the concentration of micro dust measured by β-ray measurement equipment was higher than that of micro dust sampler. According to quarterly data, it was confirmed that the data from the third quarter (July to September) showed a different trend from other periods, which is assumed to be due to weather conditions. This study indicates that automatic micro-dust measurement equipment evaluation at air pollution measuring stations during the third quarter should be excluded. The evaluation cycle should be changed from once every two years to quarterly. In addition, when the criterion for determining equivalence evaluation falls within the range of the slope and intercept values of the existing trend line, it is necessary to evaluate the R2 value together and reduce the slope from 0.9-1.1 to 0.9-1.0.

Industrial emissions, mainly from industrial complexes, are important sources of ambient Volatile Organic Compounds (VOCs). Identification of the significant VOC sources from industrial complexes has practical significance for emission reduction. VOC samples were collected from July 2019 to June 2020. A Positive Matrix Factorization (PMF) receptor model was used to evaluate the VOC sources in the area. Four sources were identified by PMF analysis, including coating-1, coating-2, printing, and vehicle exhaust. The coating-1 source was revealed to have the highest contribution (41.5%), followed by coating-2 (23.9%), printing (23.1%), and vehicle exhaust (11.6%). The source showing the highest contribution was coating emissions, originating from the northwest to southwest of the sample site. It also relates to facilities that produce auto parts. The major components of VOC emissions from the coating facilities were toluene, m,p-xylene, ethylbenzene, o-xylene, and butyl acetate. Industrial emissions should be the top priority to meet the relevant control criteria, followed by vehicular emissions. This study provides a strategy for VOC source apportionment from an industrial complex, which is helpful in the development of targeted control strategies.

This study analyses the characteristics of volatile organic compounds (VOCs) emissions from the painting and printing facilities, as well as ambient VOCs at industrial complexes in Gwangju. The major components of VOCs emissions from painting facilities were toluene, acetone, 2-butanone, ethyl acetate, ethyl benzene, o-xylene and m,p-xylene. The printing facilities mostly emitted ethyl acetate, 2-butanone, acetone and toluene. Aromatics (49.9%) and oxygenated VOCs (43.6%) were dominant in painting facilities, while oxygenated VOCs (92.7%) were the largest group in printing facilities. The total hydrocarbon concentration (THC) in printing facilities was approximately six times higher than in the painting facilities. The painting and printing facilities use many solvents. Their THC concentrations differed considerably depending on the type of prevention facilities. To reduce THC, it is necessary to improve the prevention facilities and operating conditions. The dominant species of ambient VOCs in industrial complexes were investigated with toluene, ethyl acetate, 2-butanone, ethyl benzene, m,p-xylene, butyl acetate, o-xylene, hexane and acetone. Factor analysis of ambient VOCs showed that the main sources of the VOCs were organic solvents used in painting, coating, and printing, as well as automobile emissions.

This study identified concentrations, toxicities, and sources of polycylic aromatic hydrocarbons (PAHs) and heavy metals in roadside sediment from different areas of Gwangju City. Samples were collected from 13 sites of heavy traffic area (TA), downtown area (DA) and park area (PA) during February and June in 2014. The results showed a wide distribution range of PAHs concentrations between 0.139 mg/kg and 1.740 mg/kg. The highest concentration of PAHs appeared in heavy traffic area (TA). The toxic equivalent quotients (TEQs) of PAHs in the roadside sediment ranged from 27 ng/g to 159 ng/g. The TEQs and PAHs ratio of heavy traffic area and downtown area was 9.1 to 11.0%, respectively. The contributions from potential sources to PAHs in roadside sediment were estimated by the principal component analysis (PCA) and diagnostic ratios between PAHs. Vehicular (gasoline and diesel engine) emissions were found to the predominant contributor of PAHs. The concentrations of heavy metals were highest in the heavy traffic areas. The correlation analysis among traffic intensity and heavy metals, showed that AADT correlates very strongly with Cr, Cu and Pb concentrations. From the results of pollution index (PI) calculation for roadside sediment, heavy traffic area was severly polluted by heavy metals such as Cr, Cu, Pb and Zn. Contaminants in roadside sediment were found to be much affected by the vehicles. Therefore, roadside deposited sediments would be expected to be managedon a regular basis.

Recently, the energy supply uses mostly fossil fuels such as coal, petroleum, natural gas etc... however, they are limited and they present an issue for the environment. Biomass derived energy is considered promising for reducing the emissions of CO2, the significant contributor to global warming. Also it can be converted to various forms of energy through thermochemical conversion processes. In this study, a screw gasifier has been engineered for wood biomass gasification. Waste wood chip was used as biomass and the producer gas, tar; char were then achieved by gasification in the presence of CO2. The results showed that with the increase of the gasification temperature, the producer gas increased and the tar decreased. Also, due to thermal cracking, the light tar increased by the decomposition of the gravimetric tar. And a development of char pore structure was confirmed by SEM. The gasification of biomass in the presence of CO2 at 800oC produced an increase in the concentration of carbon monoxide according to the Boudoudard reaction and an increase in the char pore surface as well as its adsorption capacity. Thus the biomass gasification in the presence of CO2 was confirmed to be effective for the production of CO and the development of char.

There are many factors to influence the amount of terpene at the forest. However, it is poorly understood whether the amount is altered by meteorological factors. In order to study correlation analysis between terpene amount and meteorological(i.e., temperature, humidity, wind speed, solar radiation) and environmental factors(i.e., oxygen, carbonb dioxide) at the artificial coniferous forest of Chamaecyparis obtusa (site 1) and Cryptomeria japonica (site 2) nearby the 1st reservoir at Mt. Moodeung, the research was executed during April to November in 2011. Forest density at site 1 was 1,692 trees/ha, being occupied with 87.2% of Chamaecyparis obtusa, higher than 925 trees/ha at site 2. Carbon dioxide at site 1 was in the range of 385∼410 ppm in June, similar to at Anmyundo(395 ppm in 2010). Solar radiation has positive correlation with ambient temperature and inversely negative with relative humidity. Main species of terpene released were α -pinene, camphene, β-pinene, cymene, δ-limonene and camphor at two sites and terpene was more effluent at spring and summer than at fall. The large amount of terpene was emitted in the afternoon than in the morning under the influence of the wind speed and the topographical property. The terpene amount has positive correlation with relative humidity and oxygen, and negative with wind speed and soil temperature. Because correlations of α-pinene and other terpene materials showed statistically significant within p=0.01. α-pinene could be suggested as the basic material in explaining the amount of other terpene materials.

The filtration tests were made in cell with a low concentrated suspension. The suspension with a concentration of cM=1.14～2.67․10-3 g/g consists of paper paint and water. The particles in the suspension have a particle size x<1㎛. The used depth filters consists of glass fibres, which are coated by polymer. The filtration in depth filters accorded in different mechanism, which were explained by physical models. The model which would be allows to make a promise of the filtration reaction. This filter media allows to get a high filtration time and a good separation rate. The Particle distribution is measured by a photon correlation spectroscopy(PCS). PCS measures particle sizes 0.03 ㎛<d<3 ㎛ in the suspension. The filtered suspension has a very low concentration Co≤5×10-4 g/g of solid in sample. The PCS also informs us about the number of the particles in the suspension. The makes it possible to calculate the concentration of the in sample.